Monk was born into a family of lawyers, but her early ambition was to become a doctor. She studied clinical psychology at the College of William and Mary (B.S., 1970) and at the New School for Social Research (M.A., 1971). Her aspirations changed abruptly, however, when she joined her husband, John White (married 1970), in one of his classes at New York University School of Law. She enrolled at Columbia University Law School, from which she graduated (1974) at the top of her class. After White spent a brief period as a law clerk, she joined (1976) the 150-lawyer litigation department of Debevoise & Plimpton LLP in New York City. She later returned there as a partner (1983–90) and as head of litigation (2002–13)

White interrupted her litigation career to serve (1978–81) as an assistant U.S. attorney in the criminal division of the Southern District of New York (SDNY). In her first terrorism case, she prosecuted a group of violent anti-Fidel Castro radicals, OMEGA 7. She actively promoted the role of women at the SDNY, appointing the first woman deputy U.S. attorney and selecting female heads of the civil division, violent group, and public corruption units. For nearly a decade (1993–2002), White was the U.S. attorney for the SDNY, the first woman to hold that office in its more-than-200-year history. In that role she specialized in prosecuting complex securities, financial-institution frauds, and international terrorism cases. Her office secured convictions against the terrorists responsible for the 1993 bombing of New York City’s World Trade Center and prosecuted Omar Abdel Rahman, who that same year had plotted to bomb the United Nations headquarters and other landmark buildings in New York City as well as U.S. aircraft over the Pacific Ocean. She and her staff went on to bring to trial those responsible for bombing the U.S. embassies in Kenya and Tanzania, and White took the unprecedented step of setting up a terrorism unit in the SDNY. Her team also investigated white-collar crimes, money laundering, official corruption, and the international drugs trade.

On February 7, 2013, Pres. Barack Obama formally nominated White for chair of the Securities and Exchange Commission (SEC). She received the unanimous approval of the U.S. Senate on April 8 and was sworn in on April 10. In 2014 White faced serious challenges to meet the SEC’s obligations to protect investors, maintain orderly and efficient securities markets, and facilitate capital formation. Later that year she noted the sharp decline in the number of companies being listed and the need for regulatory changes that take into account their impact on market quality for investors and issuers. A lack of transparency in equity markets was seen as one cause of the financial disaster that began in 2008.

Under White’s oversight, the SEC was involved in a number of high-profile cases, including a 2014 settlement with Morgan Stanley, in which the company agreed to pay $275 million for “misleading public disclosures” during the 2008 crisis. In addition, White introduced a number of regulations. Her tenure was not without controversy, however. Notably, in 2016 U.S. Sen. Elizabeth Warren called on Obama to dismiss White for failing to make corporations reveal political contributions. Later that year White announced that she was leaving office at the conclusion of Obama’s second term in January 2017. She was succeeded by Jay Clayton.